1. ELECTROSTATICS

2. Outline Electric Force, Electric fields Electric Flux and Gau  law Electric potential Capacitors and dielectric (Electric storage)

3. The physics of charged objects Study of electricity aims to understand the interaction between different charged objects. +-

4. The physics of charged objects Study of electricity aims to understand the interaction between different charged objects. ++ --

5. Structure of Matter Fundamental building blocks of the matter are atoms. + + + + + + +- - - - - - -

6. Structure of Matter Neutral atom – electron = Positive ion + + + + + + +- - - - - --

7. Structure of Matter Fundamental building blocks of the matter are atoms. + + + + + + +- - - - - - -

8. Structure of Matter Neutral atom + electron = negative ion. + + + + + + +- - - - - - - -

9. ELECTRICALLY CHARGING OBJECTS +-+ +- -+ +-+ - - - - + + - +

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12. In metals outer atomic electrons are not bound to any atoms (electron see). Charging by Induction + + + + + + + + + +

13. In metals outer atomic electrons are not bound to any atoms (electron see). + + + + + + + + + + -

14. Charging by Induction

15. Same atoms have weakly bound electrons. Electric Polarization + + + + + + + - - -- - - -

16. Same atoms have weakly bound electrons. + + + + + + + - - - - - - - +

17. Electric Polarization

18. The Electric Force

19. Coulomb’s Law Quantifies the electric force between two charges.

20. Coulomb’s Law Quantifies the electric force between two charges.

21. Coulomb’s Law Quantifies the electric force between two charges.

22. Electric Force Field Gravitational force field:

23. Electric Force Field +Q

24. Electric Force Field +Q +q

25. Electric Force Field Definition of Electric field:

26. Electric Force Field Definition of Electric field:

27. Electric Force Field + + + + +

28. The electric field due to a number of source charges is given by the expression

29. Electric Force Field

30. Electric Force Field (Linear distribution of charge)

33. Electric Force Field (Surface distribution of charge) da

34. Electric Force Field (Surface distribution of charge) da

35. Electric Force Field (Surface distribution of charge) da

36. Electric Dipole Electric dipole consists of a pair of point charges with equal size but opposite sign separated by a distance d. + -

37. Electric Dipole Electric dipole consists of a pair of point charges with equal size but opposite sign separated by a distance d. + -

38. Electric Dipole Electric dipole consists of a pair of point charges with equal size but opposite sign separated by a distance d. + -

39. Electric Dipole Electric dipole consists of a pair of point charges with equal size but opposite sign separated by a distance d. + -

40. Electric Dipole Water molecules are electric dipoles ++ -

41. Exercise 1 A point charge q = -8.0 nC is located at the origin. Find the electric field vector at the point x = 1.2 m, y = -1.6 m -

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45. Exercise 2 An electric dipole consists of a positive charge q and negative charge –q separated by a distance 2a, as shown in the figure below. Find the electric field due to these charges along the axis at the point P, which is the distance y from the origin. Assume that y>>a.

47. Vector Flux

49. Definition of flux:

50. Electric Flux

52. Gau  ’s Law

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57. Exercise 3

58. Solution Coulomb’s Law

59. Solution Infinitesimal area of disk

60. Solution Infinitesimal area of disk

61. Solution Y-component of E-field element

62. Solution

63. Y-component of E-field element

64. Solution Y-component of E-field element

65. Solution Y-component of E-field element

66. Solution Y-component of E-field element

67. Two Oppositely charged Parallel Plates (Capacitor)

69. Exercise 4

70. Electric Potential +Q +q

71. Electric Potential +Q

72. Electric Potential

75. Electric potential at position P due to a system of N source charges is given by:

76. Electric Potential Potential difference:

77. Electric Potential Potential difference:

78. Electric Potential

79. Two Oppositely charged Parallel Plates (Capacitor)

81. Capacitors and di-electrics Capacitors store electric potential energy Battery

83. Capacitors and di-electrics

85. We can therefore express the voltage across the capacitor plates as follows: Hence

86. Exercise 3 A parallel-plate capacitor has an area of A = 2 cm 2 and a plate separation of d =1mm. (a)Find its capacitance. (answer = 1.77pF) (b)If the plate separation of this capacitor is increased to 3 mm, find the capacitance. (answer = 0.59 pF).

87. Capacitors and di-electrics Capacitors in Parallel

88. Capacitors and di-electrics Di-electric material inside a parallel Electric field.

89. Capacitors and di-electrics Di-electric material between parallel capacitor plates.

90. Capacitors and di-electrics Di-electric material between parallel capacitor plates.

91. Capacitors and di-electrics Di-electric material between parallel capacitor plates.

92. Capacitors and di-electrics Di-electric material between parallel capacitor plates.

93. Capacitors and di-electrics Di-electric material between parallel capacitor plates.